1. Field of the Invention
The present invention relates to the field of the application of metal or a metal alloy in the fabrication of an integrated circuit arrangement, and more particularly, it relates to a method for electrodepositing a copper metal.
2. Description of the Related Art
Requirements for an increased performance of semiconductor chips lead to ever higher packing densities in addition to ever higher current densities in metallization planes or metallization layers of an integrated circuit (e.g., power semiconductors configured to switch a number of amperes). Problems due to electromigration and heating come to the fore and limit the performance of the components. By way of example, copper or copper alloy have been used in place of conventional tungsten or aluminum. Copper enables higher current densities and a thermal conductivity by a factor of 2. Due to the high diffusion coefficient of copper silicon, however, copper also increases risks to the transistor planes. A diffusion of copper atoms into the active regions alters, for example, the threshold voltage, the channel length or the switching time of a transistor. The diffused atoms may act as a defect, a center for charge carriers, generation or recombination, cause a shortening of the lifetime of charge carriers, and/or introduce oxidation induced stacking faults and weak points in thin oxide layers. Accordingly, a failure of a transistor may occur. Accordingly, it is necessary to prevent the diffusion of copper atoms or other atoms having a large diffusion coefficient in silicon. The barrier layer alone is not sufficient for this purpose, because it is also described to prevent a copper cross contamination within the production line.